TEM study of GaN-based nanopillar-shaped-crystals grown on a multicrystalline Si substrate

A gallium nitride-based thin film is grown on a multicrystalline Si substrate by a molecular beam epitaxy apparatus. The microstructure of the crystalline film is closely examined by transmission electron microscopy (TEM). It is revealed that the film is composed of nanopillar-shaped-crystal grains with their diameters of 100 nm and heights of 400 nm approximately. Each nanopillar-crystal grain is based on highly-ordered wurtzite crystal structure and strongly textured with its c-axis oriented perpendicular to the substrate surface. The TEM observations also evidence that there are two kinds of basal stacking faults widely distributed in the nanopillar-crystal.